Study On Modification Of ZnO-TiO₂ Composite Catalyst And Its Photocatalytic

With the serious deterioration of global environment, the environmental awareness of people are growing, and the ways to protect environment become increasingly scientific, reasonable and "green". So, the photocatalytic oxidation technology has been used extensively, especially in the treatment of organic wastewater. Usually the organic pollutant in wastewater was degraded into the non-toxic, harmless and small molecules by semiconductor catalyst at room temperature. But the semiconductor catalyst can not be full use of light in the photocatalytic reaction. Therefore, modification of the semiconductor catalyst has become a research hotspot in the photocatalytic reaction.In this article, ZnO-TiO₂ composite was prepared by sol-gel method, and through different metal to be modified. The factors of ZnO-TiO₂ composite catalyst and its modified were studied in photocatalytic degradation of reactive brilliant blue KN-R. We can obtain the optimum technology conditions to degrade the wastewater, and study the dynamic characteristics of reaction.The results show that: on the condition of calcinations temperature of 530℃, the ZnO-TiO₂ composite catalyst which was prepared by sol-gel method have many advantages, such as smaller particle size, big surface area, the significant photocatalytic performance, etc. And the 20% of the amount of TiO₂ catalyst doped has the best catalytic effect, meanwhile, XRD, SEM, TG-DSC and UV-Vis are all show the same effect.Silver, lanthanum, indium doped in ZnO-TiO₂ composite catalyst show the good effect. Meanwhile, the external factors on the photocatalytic effect also has great influence: the rare earth elements doped in ZnO-TiO₂ composite catalyst can improve the catalytic properties in the acidic conditions; But the silver and iron doped in ZnO-TiO₂ composite catalyst will have better catalytic effect in alkaline conditions; The optimum amount of catalyst is 2g·L^-1 or 3g·L^-1 for brilliant blue KN-R, too much or too little catalyst will lower the catalytic effect.?In the preparation of the catalyst, the optimum amount of lanthanum and indium doped ZnO-TiO₂ composite catalyst is 2g·L^-1, which of silver, copper and iron doped ZnO-TiO₂ composite catalyst is 3g·L^-1; The optimum initial concentration of degrading brilliant blue KN-R is about 85-100mg·L^-1, the initial concentration is not too high or too low, or it will affect the photocatalytic degradation rate and the effective use of the catalyst. When the lanthanum, silver, copper and iron doped ZnO-TiO₂ composite catalyst degrade brilliant blue KN-R, the optimum initial concentration is 85mg·L^-1. But the optimum initial concentration of Indium-doped ZnO-TiO₂ composite catalyst in the degradation of brilliant blue KN-R is 100mg·L^-1. And at a certain concentration range, the reaction of degrading brilliant blue KN-R follow first order reaction kinetics equation based on Langmuir-Hinshelwood reaction mechanism.Systematic research for ZnO-TiO₂ composite catalyst is not only enriched the theoretical basis of the photocatalytic reaction, but also provided a strong reference for industrial production and application.